Hydrogen‑bonded interfacial super‑assembly of spherical carbon superstructures for high‑performance zinc hybrid capacitors

As the demand for high-performance energy storage systems intensifies, aqueous zinc-ion hybrid capacitors (ZHCs) have emerged as a promising technology due to their high safety, low cost, and environmental friendliness. Now, researchers from Tongji University, led by Prof. Ziyang Song and Prof. Lihua Gan, have developed a novel hydrogen-bond-guided interfacial super-assembly strategy to construct spherical carbon superstructures (SCS-6) with exceptional energy storage performance. This work offers valuable insights into the design of advanced carbon cathodes for next-generation energy storage.

Why Spherical Carbon Superstructures Matter

• Ultrahigh Energy Density: The SCS-6 cathode delivers an outstanding energy density of 166 Wh kg^-1, outperforming most reported carbon-based ZHCs.
• Ultra-Long Cycle Life: The Zn||SCS-6 device maintains 95.5% capacity retention after 500,000 cycles, demonstrating exceptional durability.
• Fast Ion Transport: Unique surface-opening pores and interconnected channels enable rapid Zn²⁺ diffusion and high-rate performance.
• Dual-Ion Storage Mechanism: A proton-assisted opposite charge-carrier storage mechanism maximizes spatial charge utilization and boosts capacity.

Innovative Design and Features

• Hydrogen-Bond-Driven Assembly:
  Tetrachlorobenzoquinone (H-bond acceptor) and dimethylbenzidine (H-bond donor) self-assemble into 2D nanosheet modules, which are then compacted into 3D spherical superstructures via N–H···O hydrogen bonding.
• Hierarchical Porous Architecture:
  The resulting SCS-6 features micropores (~0.8 nm) and mesopores (2–12 nm), with a specific surface area of 2530 m² g^-1, ensuring high accessibility of active sites and efficient electrolyte infiltration.
• Rich Heteroatom Doping:
  N/O co-doping introduces zincophilic sites (e.g., carbonyl, pyridine groups) that enhance Zn²⁺ adsorption and redox activity.

Applications and Future Outlook

• High-Performance Zn-Ion Hybrid Capacitors:
  The Zn||SCS-6 device achieves 246 mAh g^-1 at 0.2 A g^-1 and 172 mAh g^-1 at 20 A g^-1, with 99.8% Coulombic efficiency over half a million cycles.
• Proton-Assisted Charge Storage:
  A dual-ion mechanism involving Zn²⁺/H⁺ co-storage via physical adsorption and chemical redox reactions significantly enhances capacity and kinetics.
• Scalable and Tunable Synthesis:
  The solvent-adaptable super-assembly process enables morphology control (e.g., flower-like, curly flake), offering flexibility for diverse energy storage applications.
• Challenges and Opportunities:
  Future research will focus on mass-loading scalability, electrolyte optimization, and mechanical flexibility for wearable and grid-scale energy systems.

This comprehensive study provides a roadmap for hydrogen-bond-guided carbon superstructure design, highlighting the importance of interfacial engineering, hierarchical porosity, and heteroatom doping in advancing high-energy, long-life energy storage technologies.

Stay tuned for more groundbreaking work from Prof. Ziyang Song and Prof. Lihua Gan at Tongji University!